In industrial plants, especially in power plants, condition monitoring of main systems (e.g. turbines and/or generators) sub-systems (e.g. water-steam-cycle) and components (e.g. pumps, motors, drives, valves, pipes, bearings etc.) of the plants is essential to guarantee reliable operation. Condition monitoring often includes a quasi non-stop acquisition and storing of data relevant for the operation of the plant.
In order to adjust operation parameters during operation of the plant, schedule maintenance and repair work, and to minimize safety risks, accurate data about the condition of numerous plant assets must be gathered and analyzed. The nature of a.m. data needed is manifold and the impact of said data on actual plant failures is often hard to determine.
Typical examples of condition monitoring data are vibration data (e.g. of turbines or pumps, often acquired by vibration sensors and analyzed by a specialized evaluation device using spectrum analysis or the like), temperature and/or pressure data (e.g. of boilers, acquired inside the boiler via sensors or calculated indirectly using related data), volume data (e.g. throughput of a pipeline) and so on.
There are technical means, e.g. sensors, to collect most of the desired data. However, for a complete and reliable picture of a plant's actual condition, the amount of data needed is enormous.
This is a problem both in terms of installation costs of sensors, and in terms of efforts to analyze the resulting sensor data.
As a consequence, the majority of plant owners cannot afford an all-embracing monitoring of all plant assets.
Therefore, unscheduled drop outs of production are inevitable, often resulting in a loss of income and/or high penalties.
Known methods of monitoring the condition of industrial plants may include:
Collecting data and reporting related values, e.g. on-line or off-line statuses, using sensors attached to the components to be monitored; said sensors may include vibration sensors for rotating machinery (e.g. generators, turbines) and/or thermography (e.g. temperature) sensors for boilers.
If a component is being monitored on-line, sensors are usually connected to an evaluation system, which analyzes the data and prompts appropriate messages related to its condition to the operator, e.g. on a computer screen or large screen display.
Off-line sensors do not necessarily need to be connected to an evaluation system; data can be collected on demand, e.g. using a portable computer.
Any kind of known methods of sensor based monitoring are usually extremely costly.
Not only the actual technical equipment needed, but also the appropriate commissioning and adjusting of the sensors to the specific needs and environmental conditions, take more efforts and financial investments than typical plant owners are able or willing to spend.
And/or
Inspecting machinery by frequent walks across the plant.
Specialist engineers may inspect machinery by a.m. frequent “walk downs”.
The main “sensor” used for inspection here is human perception.
Due to their knowledge and experience, these engineers are able to detect a broad range of failures.
However, symptoms of many failures simply cannot be sensed without technical aids.
For example, bearings, which start becoming faulty, can only rarely by detected solely by human perception, or the unwanted change of magnetic flux in a pump cannot at all be noticed by man.
Furthermore, long term changes of a machine's characteristic occurring in the course of time are very hard to realize since there no direct comparison available with a regular operation mode.